Having just gone over my 1934 Genco Subway Special, it is obviously battery powered....I just picked up a Chicago Coin Sensation of 1937 and it is electric...but I could not imagine technology changed so much in only a couple of years. It looks as if the CC projects the image onto the back of the backglass to show the score. It also has a tilt bob and gates that open and close. So I guess the question is....when did batteries stop being a part of the old pin technology??? Thanks Mike

The first battery operated machines appeared in 1933, Harry Williams made the first.
By 1934, machines were redesigned to be used with electrical outlets allowing for new types of sounds,
music, lights, lighted backglass, and other features.http://inventors.about.com/od/pstart.../a/pinball.htm

About that time(mid to late 30's) all kinds battery eliminators gained popularity. Most designed for radio sets. The filament supply would deliver low volts and replace a couple 1.5 Volt dry cells. Manufactures started making product specific battery eliminators. There were scores of companies making amusement devices some had options for batteries and/or battery eliminator. I have seen photos and flyers of vintage battery eliminators for old pinballs. I can't seem to find one today, but ... Would I tell You A Lie ???